Advanced graphs and analysis

QtiPlot is a free application that is very similar to the popular Origin program. It offers almost identical menu structure and operation of the program is also very similar. QtiPlot lacks some of the graphs (e.g. bubble) and advanced statistical functions, and final graphs are not often so aesthetically well done as the graphs used by Origin. However, among the available free tools for analysis and visualisation of functions this is probably the strongest and best equipped.